The long term goals of the research are to identify and understand the details of the elaborate regulatory mechanisms utilized by Pseudomonas aeruginosa that result in biofilm formation and chronic infections of compromised individuals. Pseudomonas aeruginosa is the quintessential opportunistic pathogen. Chronic Pseudomonas aeruginosa infections of the lung are the most common cause of death in cystic fibrosis patients, underscoring the notoriety of Pseudomonas aeruginosa as a pathogen. There are many keys to the ability of this bacterium to colonize and survive in environments such as the cystic fibrosis lung and to thwart antibiotic regimes and circumvent the body's immune responses. These include the ability to form biofilms, to produce the exomucopolysaccharide alginate - a natural barrier and virulence factor, the ability to act as a community to coordinate biological responses via multiple quorum sensing systems, and the ability to sense and adapt to conditions of high oxidative stress, iron limitation, and available carbon sources. Not surprisingly, these attributes are tightly intertwined, and together reflect the complexity and elegance of the regulatory network in Pseudomonas aeruginosa. We have discovered a novel multi-protein complex in Pseudomonas aeruginosa that includes proteins integral to quorum sensing, alginate biosynthesis regulation, the oxidative stress response and the response to environmental iron and carbon, including the novel protein AlgH whose function is not understood. Based on the identities of the proteins in the complex, and based on fact that these responses are integral to biofilm formation and colonization and survival in the cystic fibrosis lung, it functions to integrate the responses to a variety of key biological signals and is essential for survival in the cystic fibrosis lung. Furthermore, because these systems (the quorum sensing system(s), the alginate biosynthesis regulatory system, etc.) are good targets for controlling Pseudomonas aeruginosa infections, targeting this novel protein complex pharmaceutically should be quite advantageous as multiple systems will simultaneously be disrupted. Our overall hypothesis is that the intricate regulatory and adaptive mechanisms used by Pseudomonas aeruginosa to survive and thrive in the cystic fibrosis lung as biofilms can be disrupted and controlled by regulating the formation/functions) of this multi-protein complex. To begin to address this broad hypothesis, we propose to; 1) Establish the requirements for formation of the multi-protein complex, 2) Identify the interprotein interactions in the multi-protein complex and determine the structural topology of the complex, 3) Solve the structures of component proteins of the multi-protein complex at high resolution, and 4) Initiate functional studies of the complex. The results of the research should provide important new strategies for prevention and treatment of infections by bacteria that form biofilms. [unreadable] [unreadable] [unreadable]